本程序实现了本地摄像头数据的获取解码和显示。是基于FFmpeg的libavdevice类库最简单的例子。通过该例子，可以学习FFmpeg中 libavdevice类库的使用方法。
本程序在Windows下可以使用2种方式读取摄像头数据：
1.VFW: Video for Windows 屏幕捕捉设备。注意输入URL是设备的序号，从0至9。
2.dshow: 使用Directshow。注意作者机器上的摄像头设备名称是“Integrated Camera”，使用的时候需要改成自己电脑上摄像头设备的名称。
在Linux下则可以使用video4linux2读取摄像头设备。
/**
* 最简单的基于FFmpeg的AVDevice例子（读取摄像头）
* Simplest FFmpeg Device (Read Camera)
*
* 雷霄骅 Lei Xiaohua
* leixiaohua1020@126.com
* 中国传媒大学/数字电视技术
* Communication University of China / Digital TV Technology
* http://blog.csdn.net/leixiaohua1020
*
* 本程序实现了本地摄像头数据的获取解码和显示。是基于FFmpeg
* 的libavdevice类库最简单的例子。通过该例子，可以学习FFmpeg中
* libavdevice类库的使用方法。
* 本程序在Windows下可以使用2种方式读取摄像头数据：
* 1.VFW: Video for Windows 屏幕捕捉设备。注意输入URL是设备的序号，
* 从0至9。
* 2.dshow: 使用Directshow。注意作者机器上的摄像头设备名称是
* “Integrated Camera”，使用的时候需要改成自己电脑上摄像头设
* 备的名称。
* 在Linux下则可以使用video4linux2读取摄像头设备。
*
* This software read data from Computer's Camera and play it.
* It's the simplest example about usage of FFmpeg's libavdevice Library.
* It's suiltable for the beginner of FFmpeg.
* This software support 2 methods to read camera in Microsoft Windows:
* 1.gdigrab: VfW (Video for Windows) capture input device.
* The filename passed as input is the capture driver number,
* ranging from 0 to 9.
* 2.dshow: Use Directshow. Camera's name in author's computer is
* "Integrated Camera".
* It use video4linux2 to read Camera in Linux.
*
*/
#include <stdio.h>
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavdevice/avdevice.h"
//SDL
#include "sdl/SDL.h"
#include "sdl/SDL_thread.h"
};
//Output YUV420P
#define OUTPUT_YUV420P 0
//'1' Use Dshow
//'0' Use VFW
#define USE_DSHOW 0
//Refresh Event
#define SFM_REFRESH_EVENT (SDL_USEREVENT + 1)
int thread_exit=0;
int sfp_refresh_thread(void *opaque)
{
while (thread_exit==0) {
SDL_Event event;
event.type = SFM_REFRESH_EVENT;
SDL_PushEvent(&event);
SDL_Delay(40);
}
return 0;
}
//Show Device
void show_dshow_device(){
AVFormatContext *pFormatCtx = avformat_alloc_context();
AVDictionary* options = NULL;
av_dict_set(&options,"list_devices","true",0);
AVInputFormat *iformat = av_find_input_format("dshow");
printf("Device Info=============\n");
avformat_open_input(&pFormatCtx,"video=dummy",iformat,&options);
printf("========================\n");
}
//Show Device Option
void show_dshow_device_option(){
AVFormatContext *pFormatCtx = avformat_alloc_context();
AVDictionary* options = NULL;
av_dict_set(&options,"list_options","true",0);
AVInputFormat *iformat = av_find_input_format("dshow");
printf("Device Option Info======\n");
avformat_open_input(&pFormatCtx,"video=Integrated Camera",iformat,&options);
printf("========================\n");
}
//Show VFW Device
void show_vfw_device(){
AVFormatContext *pFormatCtx = avformat_alloc_context();
AVInputFormat *iformat = av_find_input_format("vfwcap");
printf("VFW Device Info======\n");
avformat_open_input(&pFormatCtx,"list",iformat,NULL);
printf("=====================\n");
}
int main(int argc, char* argv[])
{
AVFormatContext *pFormatCtx;
int i, videoindex;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
av_register_all();
avformat_network_init();
pFormatCtx = avformat_alloc_context();
//Open File
//char filepath[]="src01_480x272_22.h265";
//avformat_open_input(&pFormatCtx,filepath,NULL,NULL)
//Register Device
avdevice_register_all();
//Windows
#ifdef _WIN32
//Show Dshow Device
show_dshow_device();
//Show Device Options
show_dshow_device_option();
//Show VFW Options
show_vfw_device();
#if USE_DSHOW
AVInputFormat *ifmt=av_find_input_format("dshow");
//Set own video device's name
if(avformat_open_input(&pFormatCtx,"video=Integrated Camera",ifmt,NULL)!=0){
printf("Couldn't open input stream.（无法打开输入流）\n");
return -1;
}
#else
AVInputFormat *ifmt=av_find_input_format("vfwcap");
if(avformat_open_input(&pFormatCtx,"0",ifmt,NULL)!=0){
printf("Couldn't open input stream.（无法打开输入流）\n");
return -1;
}
#endif
#endif
//Linux
#ifdef linux
AVInputFormat *ifmt=av_find_input_format("video4linux2");
if(avformat_open_input(&pFormatCtx,"/dev/video0",ifmt,NULL)!=0){
printf("Couldn't open input stream.（无法打开输入流）\n");
return -1;
}
#endif
if(avformat_find_stream_info(pFormatCtx,NULL)<0)
{
printf("Couldn't find stream information.（无法获取流信息）\n");
return -1;
}
videoindex=-1;
for(i=0; i<pFormatCtx->nb_streams; i++)
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
{
videoindex=i;
break;
}
if(videoindex==-1)
{
printf("Couldn't find a video stream.（没有找到视频流）\n");
return -1;
}
pCodecCtx=pFormatCtx->streams[videoindex]->codec;
pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
if(pCodec==NULL)
{
printf("Codec not found.（没有找到解码器）\n");
return -1;
}
if(avcodec_open2(pCodecCtx, pCodec,NULL)<0)
{
printf("Could not open codec.（无法打开解码器）\n");
return -1;
}
AVFrame *pFrame,*pFrameYUV;
pFrame=avcodec_alloc_frame();
pFrameYUV=avcodec_alloc_frame();
uint8_t *out_buffer=(uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));
avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
//SDL----------------------------
if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
printf( "Could not initialize SDL - %s\n", SDL_GetError());
return -1;
}
int screen_w=0,screen_h=0;
SDL_Surface *screen;
screen_w = pCodecCtx->width;
screen_h = pCodecCtx->height;
screen = SDL_SetVideoMode(screen_w, screen_h, 0,0);
if(!screen) {
printf("SDL: could not set video mode - exiting:%s\n",SDL_GetError());
return -1;
}
SDL_Overlay *bmp;
bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,SDL_YV12_OVERLAY, screen);
SDL_Rect rect;
rect.x = 0;
rect.y = 0;
rect.w = screen_w;
rect.h = screen_h;
//SDL End------------------------
int ret, got_picture;
AVPacket *packet=(AVPacket *)av_malloc(sizeof(AVPacket));
//Output Information-----------------------------
printf("File Information（文件信息）---------------------\n");
av_dump_format(pFormatCtx,0,NULL,0);
printf("-------------------------------------------------\n");
#if OUTPUT_YUV420P
FILE *fp_yuv=fopen("output.yuv","wb+");
#endif
struct SwsContext *img_convert_ctx;
img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
//------------------------------
SDL_Thread *video_tid = SDL_CreateThread(sfp_refresh_thread,NULL);
//
SDL_WM_SetCaption("Simple FFmpeg Read Camera",NULL);
//Event Loop
SDL_Event event;
for (;;) {
//Wait
SDL_WaitEvent(&event);
if(event.type==SFM_REFRESH_EVENT){
//------------------------------
if(av_read_frame(pFormatCtx, packet)>=0){
if(packet->stream_index==videoindex){
ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
if(ret < 0){
printf("Decode Error.（解码错误）\n");
return -1;
}
if(got_picture){
sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
#if OUTPUT_YUV420P
int y_size=pCodecCtx->width*pCodecCtx->height;
fwrite(pFrameYUV->data[0],1,y_size,fp_yuv); //Y
fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv); //U
fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv); //V
#endif
SDL_LockYUVOverlay(bmp);
bmp->pixels[0]=pFrameYUV->data[0];
bmp->pixels[2]=pFrameYUV->data[1];
bmp->pixels[1]=pFrameYUV->data[2];
bmp->pitches[0]=pFrameYUV->linesize[0];
bmp->pitches[2]=pFrameYUV->linesize[1];
bmp->pitches[1]=pFrameYUV->linesize[2];
SDL_UnlockYUVOverlay(bmp);
//测试自己填充数据----------------
SDL_DisplayYUVOverlay(bmp, &rect);
}
}
av_free_packet(packet);
}else{
//Exit Thread
thread_exit=1;
break;
}
}else if(event.type==SDL_QUIT){
thread_exit=1;
break;
}
}
sws_freeContext(img_convert_ctx);
#if OUTPUT_YUV420P
fclose(fp_yuv);
#endif
SDL_Quit();
av_free(out_buffer);
av_free(pFrameYUV);
avcodec_close(pCodecCtx);
avformat_close_input(&pFormatCtx);
return 0;
}
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